1. Field of the Invention
THE PRESENT INVENTION relates to a webbing belt, and more particularly, but not exclusively, relates to a webbing belt suitable for use as a safety-belt in a motor vehicle.
2. Description of Related Art
Webbing belts are used as safety-belts in motor vehicles and also in aircraft, but webbing belts also find other applications, for example, as safety-belts incorporated in harnesses for climbers, window cleaners, etc.
Webbing belts, especially webbing belts used as seat-belts, are woven from warp and weft yarns, with the warp and weft yarns typically being multifilament yarns. Belts formed using such a technique will be very pliable.
It is desirable to make a webbing belt which is relatively stiff in the transverse direction, especially when the belt is to be used as a safety-belt in a motor vehicle, to spread the load which is applied to the vehicle occupant by the belt when an accident occurs. Transverse stiffness can be obtained in a belt by using weft yarns which are not of a multifilament construction, but which, instead, are monofilament weft yarns. Other significant advantages of using monofilament weft yarns is that they improve the reality properties of a safety-belt, meaning that the safety-belt does not twist as easily when being wound onto, or paid-out from, a retractor reel. Also, reduced twist means that the resulting safety-belt will be more comfortable for a vehicle occupant to wear.
A problem that arises when using monofilament weft yarns in the manufacture of a belt is that the edges of the belt will be very hard. This is clearly undesirable, especially in the context of a belt which is to be used as a seat-belt in a motor vehicle, especially where the belt may rub against the neck of a seat occupant.
It has been proposed before to provide a relatively soft edge for a belt which has monofilament weft yarns, by using an extra weft yarn and a knitting process at the edge portion. A belt of this type is disclosed is WO 01/48285. Because the described technique requires the use of an extra weft yarn and an additional operation, the technique is relatively costly and time-consuming.
It has also been proposed to use two weft yarns in parallel, namely a monofilament yarn and a multifilament yarn. The monofilament yarns are woven in such a way that each pass of the monofilament yarn ends at a point spaced from the edge of the belt, so that the monofilament yarns are always spaced a predetermined distance from the edge of the belt. Thus, in the edge region of the belt, there are only the relatively soft multifilament yarns. This arrangement is relatively complicated and requires provision of additional weft yarns.
It has also been proposed to weave a soft profile at the edge of the belt, as shown in DE 2,446,837, and it has even been proposed to weave a loop of fabric at the edge of the belt to obtain a hollow section, as shown in DE 2,508,732. All of these arrangements require special weaving apparatus or provide an edge portion of a substantially greater thickness than the central region of a belt. This is clearly undesirable, especially where the belt is to be wound on to a retractor spool.